458 Journal of Agricultural Research voi. xvni, no. 9 



LIFE HISTORY 

 SUMMARY 



At La Fayette, Ind., Oscinis frit winters in the larval stage in winter 

 wheat. Following the emergence of this brood as adults in the spring, 

 there are four summer broods. 



DETAILED STUDIES 



METHODS 



On account of the minute size of the fly and its disinclination to lay 

 eggs in cages, considerable difficulty was encountered in running a series 

 of broods through the season, as well as in obtaining other details. The 

 methods which finally proved successful are, therefore, believed to be of 

 sufficient importance to justify a rather full description. 



Wheat sown in the garden in September, 191 5, became infested that 

 fall. On March 30 and April 11, 191 6, portions of it were dug up, placed 

 in pans of earth, and covered with glass cylinders 8 inches in diameter 

 with cheesecloth tops. Records of spring emergence were made from 

 these. In removing the adults, advantage was taken of their natural 

 inclination to go to light. The cage was opened in the house close to a 

 south window on which the sun was shining. The flies, as soon as given 

 their freedom, would fly toward the window, alight on a swiss curtain 

 before it, and begin to walk upward. They were then easily secured in 

 numbered homeopathic vials, in each of which a small drop of sirup and 

 one of water had previously been placed. In these vials, tightly corked, 

 adults were kept for some time, frequently 20 days or more, and in one 

 instance 49, by changing the vial occasionally. 



Breeding cages were prepared by placing earth known to be free from 

 insects in 6-inch flowerpots, planting about 10 kernels of wheat close 

 together in the middle of each, and covering with a lantern globe topped 

 with cheesecloth. In seven or eight days under outdoor summer con- 

 ditions the wheat was from i to 2 inches high, the proper stage for 

 introducing the flies. A male and female were placed in the same vial 

 and introduced into the cage by simply tipping up the lantern globe 

 and setting the vial upright in the earth, removing the thumb from the 

 mouth of the vial just as the globe was replaced. This method was not 

 quite satisfactory, but only a few flies escaped. Their inclination to 

 walk upward caused them to leave the vial at once if it was upright, but 

 if it was horizontal they sometimes remained in it a long time, and even 

 failed entirely to find their way out. 



In the cage the flies were inactive most of the time, usually resting 

 on the cloth at the top but occasionally visiting the plants, where they 

 appeared to lick up a nutritious exudation. The addition of sirup did 

 not lengthen their lives, and they soon died in cages without plants. 



